People make microservices way too small sometimes. Then you have the opposite problem with people trying to cram everything into one system. You need to recognize when some functions are related and should go together, or when something has a weird dependency and should just be separate.
Not enough info. What are you trying to actually accomplish here? If you’re stress testing and trying to measure how fast a server can process all those requests, use something like jmeter. You can tell it to do 100 concurrent threads with 10000 requests each, then call it a day.